{{tag>projects cloud club computing virtualization machines VMs AWS Azure GCP}}


[[cloud_club|About the Club]]

==== Cloud Club Topics - Domain Name Servers ( DNS ) ====

==== Name servers ====
  - Creating servers is great and memorizing IP addresses on a small network is OK. But, names are a lot easier to remember than IP address, especially on a large netowrk ( eg. the internet ).
  - The original way to name servers is to use a file ( /etc/hosts )

==== Hands-On naming servers ====
  - Edit the /etc/hosts file on your server(s). It should look like the following <code>
27.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1        localhost localhost.localdomain localhost6 localhost6.localdomain6
</code>
  - Add the following content at the bottom - ( replace the webserver IPs and names + the LB IP and name )<code>
<webserver_1_IP>  <webserver_1_name>.cloudclub.edu
<webserver_2_IP>  <webserver_2_name>.cloudclub.edu
<LB_IP>           <LB_name>.cloudclub.edu
</code>
  - View the websites with curl<code>
curl http://<webserver_1_name>.cloudclub.edu/
curl http://<webserver_2_name>.cloudclub.edu/
curl http://<LB_name>.cloudclub.edu/
</code>



==== Understanding DNS ====
  - DNS is the Domain Name System
    - Examples of DNS software:

^ Name                ^ Supported OS                                      ^
| Bind 9              | Linux, Windows Server 2012+, Windows 10+          |
| DNSmasq             | Linux, Mac                                        |
      

==== Hands-on installing a DNS server ====
  - Create a Rocky Linux server ( if you don't already have one )
    - Assign an IP address from your range
    - Install bind9 ( dns server software )<code>
sudo dnf install bind bind-utils -y
sudo systemctl enable --now bind
</code>

==== Hands-on configure a DNS server ====
  - Edit the config file ( /etc/named.conf )
    - Configure main options<code>
  options {
            listen-on port 53 { any; };
            listen-on-v6 port 53 { any; };
            directory       "/var/named";
            ...
            allow-query { any; };
        };
</code>
    - Define you domain<code>
zone "cloudclub.edu" {
        type master;
        file "/var/named/cloudclub.edu.db";
       };
</code>
  - Create the directory if it doesn't already exist ( it does on our server )<code>
sudo mkdir -p /var/named
</code>
  - Create the zone file ( /var/named/cloudclub.edu.db )<code>
$ttl 38400
cloudclub.edu.     IN      SOA     dns.cloudclub.edu. admin.cloudclub.edu. (
                        1611368586
                        10800
                        3600
                        604800
                        38400 )
cloudclub.edu.          IN      NS      dns.cloudclub.edu.
dns.cloudclub.edu.      IN      A       192.168.1.11
repo.cloudclub.edu.     IN      A       192.168.1.11
</code>
  - Enable/start bind service<code>
sudo sytemctl enable --now named
</code>
  - Check your configuration doesn't have errors<code>
sudo named-checkconf /etc/named.conf
</code>
  - Check that you get a result from a basic query of your domain<code>
sudo dig @localhost cloudclub.edu
</code>
  - Open the DNS port/service in the firewall<code>
sudo firewall-cmd --permanent --add-service=dns
sudo firewall-cmd --reload
</code>
  - Test query your DNS server for one of the addresses you added<code>
dig @192.168.1.11 repo.cloudclub.edu


; <<>> DiG 9.16.23-RH <<>> repo.cloudclub.edu
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 394
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: 81331712b590bb610100000068085e3f33d592afa55f8a0c (good)
;; QUESTION SECTION:
;repo.cloudclub.edu.		IN	A

;; ANSWER SECTION:
repo.cloudclub.edu.	38400	IN	A	192.168.1.11

;; Query time: 2 msec
;; SERVER: 192.168.1.11#53(192.168.1.11)
;; WHEN: Tue Apr 22 20:27:59 PDT 2025
;; MSG SIZE  rcvd: 91

</code>
  - Request the short result with **__only__** the answer<code>
dig +short @192.168.1.11 repo.cloudclub.edu

192.168.1.11

</code>